Therapeutic regeneration of diseased or damaged myocardium with pluripotent stem (PS) cells depends on the ability to efficiently pre-differentiate PS cells in vitro to specialized endpoints within the coronary vascular and cardiomyocyte lineages. The overall objective of this PPG is to elucidate mechanisms by which homogeneous populations of cardiomyogenic and coronary vascular cells can be induced in a fashion compatible with therapeutic transplantation. This objective will be approached by adhering to an over-riding theme, based on the interplay between endoderm and mesoderm lineages during embryonic development, that specific endodermal lineages induce differentiation of the cardiomyogenic and proepicardium-derived coronary vascular lineages. Subprojects 1 and 4 will focus on how endoderm-secreted growth factors mediate induction of hESCs into Nkx-2.5-positive and Islet 1-positive cardiomyocyte progenitors, while Subproject 2 focuses on how transcription factors mediate these lineage decisions. This will be complemented by Subproject 3 which will investigate endoderm's role during specification of the proepicardium and its progeny which includes coronary endothelial and smooth muscle coronary vascular lineages, in pluripotent ESCs. Synergy created by these interacting subprojects will facilitate the generation of hESC-derived cardiomyogenic and coronary vascular cells that are suitable for transplantation into infarcted hearts of animal models. Using a combination of these cells which confers optimal regeneration, transplantation refinements including effects of reperfusion, numbers of transplanted cells and timing of transplantation will be evaluated in terms of functional outcomes assessed by echocardiographic and ventricular pressure measurements, as well as by histological outcomes with the objective of engrafting damaged myocardium with a vascularized, beating syncytium of cardiomyocytes that restores cardiac function. Success achieving these tasks will be promoted by synergy provided from Administrative (A), ES Cell (B), Cardiovascular Physiology (C) and Histology &Imaging (D) Cores